Re: [PATCH net v2 2/6] mptcp: pm: fix ADD_ADDR timer infinite retry on option space insufficient

[Li Xiasong]

Hi, Matt

On 5/17/2026 1:50 PM, Matthieu Baerts wrote:
> Hello,
> 
> On 15/05/2026 06:27, Matthieu Baerts (NGI0) wrote:
>> From: Li Xiasong <lixiasong1@xxxxxxxxxx>
>>
>> When TCP option space is insufficient (e.g., when sending ADD_ADDR with an
>> IPv6 address and port while tcp_timestamps is enabled), the original code
>> jumped to out_unlock without clearing the addr_signal flag. This caused
>> mptcp_pm_add_timer to keep rescheduling indefinitely, not sending ADD_ADDR,
>> preventing subsequent addresses in the endpoint list from being announced.
> 
> (...)
> 
>> diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
>> index 3c152bf66cd5..3e770c7407e1 100644
>> --- a/net/mptcp/pm.c
>> +++ b/net/mptcp/pm.c
> 
> (...)
> 
>> @@ -414,8 +420,12 @@ mptcp_pm_del_add_timer(struct mptcp_sock *msk,
>>  	/* Note: entry might have been removed by another thread.
>>  	 * We hold rcu_read_lock() to ensure it is not freed under us.
>>  	 */
>> -	if (stop_timer)
>> -		sk_stop_timer_sync(sk, &entry->add_timer);
> FYI, sashiko found a pre-existing issue here, but I guess that's not
> blocking this series.
> 
> https://sashiko.dev/#/patchset/20260515-net-mptcp-misc-fixes-7-1-rc4-v2-0-701e96419f2f%40kernel.org
> 
> @Li: just to know what I do with this pre-existing issue, do you plan to
> look at it?
> 
> Just in case, I just opened:
> 
>   https://github.com/multipath-tcp/mptcp_net-next/issues/623
> 

Thanks for the heads-up. I’ll take a look at #623 separately and follow up
there.

Best regards,
Li Xiasong